1. Field of the Invention
The present invention relates to a transformed Bacillus host capable of expressing a cellulose binding domain polypeptide, a Bacillus expression vector, and a method for producing a cellulose binding domain in a Bacillus host cell.
2. Description of Related Art
Focus on the CBD as a functional domain has involved the synthesis of the domain as a single domain molecule.
One of the first pure CBD's was obtained as synthesized by automated solid phase synthesis (Kraulis P. et al. (1989)).
It has been shown that CBDs can be expressed in E. coli as functional single domains, see e.g.: Ong E. et al. (1993), wherein it is disclosed that expression using E. coli results in a yield of 33 mg CBD per liter of culture fluid in the periplasma of the cells.
Recently, a double fungal CBD (a dimer) has also succesfully been expressed in E. coli, see Linder M. Et al. (1996).
However, the expression of CBD's in E. coli is not a true extracellular expression and results in an unsatisfactory yield which is too low for industrial scale production of CBD.
U.S. Pat. No. 5,525,195, U.S. Pat. No. 5,536,655, WO 91/17244 and WO 91/10732 discloses expression in a Bacillus host cell of an endoglucanase enzyme which has the catalytically active domain operably linked to a cellulose binding domain.
Accordingly, it is the object of the present invention to provide a method for producing CBD in a high yield, preferably by means of a conventional fermentation technique involving extracellular production of the CBD which in turn makes the use of CBD in industrial applications economically feasible.